Received: 25 September 2020
Accepted: 4 February 2021
First Online: 3 March 2021
Ethics approval and consent to participate
: The data of the normative sample were collected within the Multitopic Survey 2004 organized by the Robert-Koch-Institute (Berlin) with the assistance of a demographic consulting company (USUMA, Berlin, Germany). The survey met the ethical guidelines of the International Code of Marketing and Social Research Practice by the International Chamber of Commerce and the European Society of Opinion and Marketing Research. The study was reviewed and approved by the ethics review board of the Robert Koch Institute. The study participants were visited at home and interviewed by trained interviewers in face-to-face interviews after they had consented a privacy statement.
: The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.